The present invention relates generally to an antenna used for a wireless apparatus, and more particularly to an antenna that provides three or more resonance frequencies, and a wireless apparatus having the antenna. The present invention is suitable, for example, for a triple band antenna installed in a cellular phone such as a personal digital cellular (“PDC”), a personal handy phone system (“PHS”), and another mobile communication terminal, which are generally referred to as “mobile radio communication apparatuses.”
Along with the recent widespread of the mobile radio communication apparatuses, the cellular phone is increasingly required for expanded communication services and further miniaturization. The conventional cellular phone provides services in one or more resonance frequency bands, such as 2 GHz band and 800 MHz band.
Use of a built-in antenna corresponding to each band is necessary to provide communication services in two or more resonance frequency bands, i.e., multi-band services. In that case, use of two or more resonance antennas or single band antennas for the cellular phone, each of which provides one resonance frequency band or a single band, would scarify the miniaturization. Accordingly, a resonance antenna that provides two resonance frequency bands (called a dual band antenna) is proposed.
Prior art include, for example, PCT International Publications Nos. 96/34426 and 02/13312, and Japanese Patent Application, Publication No. 2004-266311.
The cellular phones will be likely to expand the number of resonance frequencies for communication services in the near future, such as an additional 1.7 GHz band, but no triple band antenna that provides three resonance frequencies (triple band) has yet been proposed. Currently, the triple band needs to use three single band antennas or a combination of one dual band antenna and one single band antenna. As discussed above, use of plural antennas hinders the miniaturization of the cellular phone.